fix: address remaining Cubic review comments (P2 issues)

- Add content-based fallback matching for todos without ids

- Add TODO comment for exported but unused SDK functions

- Add resetStorageClient() for test isolation

- Fixes todo duplication risk on beta (SQLite backend)

src/tools/session-manager/storage.ts

@@ -17,6 +17,10 @@ export function setStorageClient(client: PluginInput["client"]): void {
   sdkClient = client
 }
 
+export function resetStorageClient(): void {
+  sdkClient = null
+}
+
 export async function getMainSessions(options: GetMainSessionsOptions): Promise<SessionMetadata[]> {
   // Beta mode: use SDK
   if (isSqliteBackend() && sdkClient) {